Reactive particulate resin and method for its production

ABSTRACT

Disclosed is a reactive particulate resin which is characterized by each particle thereof having a core of three-dimensionally crosslinked resin having a degree of crosslinking from 0.05 to 2.0 mmol/g, and a shell formed thereon having a radical-polymerizable ethylenic unsaturated bond and is formed by polymerization of one or more polyfunctional monomers (A) and one or more non-aromatic radical-polymerizable monomers (B), the polyfunctional monomer (A) having in the molecule (a) at least one species of 1-monosubstituted and 1,1-disubstituted radical-polymerizable ethylenic unsaturated bonds and also (b) at least one of at least one species of 1,2-disubstituted, 1,1,2-trisubstituted, and 1,1,2,2-tetrasubstituted radical-polymerizable ethylenic unsaturated bonds.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 07/982,287,filed Nov. 25, 1992, abandoned, which is a continuation-in-part ofapplication 07/966,744, filed Oct. 26, 1992, pending, which is acontinuation-in-part of application Ser. No. 07/753,480, filed Sept. 3,1991.

FIELD OF THE INVENTION

The present invention relates to a new particulate resin ofthree-dimensional structure having crosslinkable reactive groups on theparticle surface and a method for producing the same.

The reactive particulate resin of the present invention can beincorporated into a thermosetting resin composition for thermoformingsuch as SMC (sheet molding compound), BMC (bulk molding compound) andother premix materials to be made into bathtubs, washstands, kitchencounters, etc. having a translucent marble pattern.

Having radical polymerizable unsaturated bond, the reactive particulateresin of the present invention can be also applied to a radical curingcoating material, a curing resin composition by active energy rays, suchas UV a curing coating material, a printing material, a resist material,a photo shaping system etc., an oxidative polymerization resincomposition, other than the application of the above-mentioned SMC, BMC,etc.

DESCRIPTION OF THE PRIOR ART

In general, SMC and BMC used for pressure thermoforming are subject tocracking and dull surface on account of their shrinkage on curing. Toeliminate this drawback, they are incorporated with a thermoplasticresin (such as polymethyl methacrylate, polystyrene, polyethylene,polyvinyl acetate, and copolymers thereof) in the form of particles orin the form of dispersion or solution in a crosslinkable monomer. Thethermoplastic resin reduces their shrinkage. It separates from thematrix on account of the abrupt heat generation that occurs when thethermosetting resin cures. At the same time, it greatly expands onheating to form micropores and microcracks which cancel out the cureshrinkage of the thermosetting resin. Thus the molded product as a wholedecreases in shrinkage.

A serious disadvantage of using a thermoplastic resin for the reductionof cure shrinkage is an impaired translucent appearance of the moldedproduct. This results from the light scattering that takes place at theinterface between the matrix and the thermoplastic resin, micropores,and microcracks. In the case of bathtub or washstand, which comes intocontact with hot water, the thermoplastic resin incorporated thereinposes another problem associated with durability (e.g., heat resistanceand water resistance) because it separates from the matrix at theinterface, permitting the entrance of water into micropores and causingthe whitening and discoloration of the molded product.

The conventional reactive particulate resin of three-dimensionalstructure is produced by polymerization of a polyfunctional monomer anda polymerizable monomer. It comes in the following two types and others.

The first one is a particulate resin which is prepared in three steps.The first step involves the synthesis of crosslinked fine particles froma polyfunctional monomer having at least two α,β-ethylenic unsaturatedbonds and a polymerizable monomer having an α,β-ethylenic unsaturatedbond. The second step involves the introduction of active hydrogen tothe particle surface by the use of a hydrophilic monomer or oligomerhaving active hydrogen. The third step involves the introduction ofethylenic unsaturated bonds to the particle surface through the reactionof the active hydrogen with a monomer having a terminal ethylenicunsaturated bond. (See Japanese Patent Laid-open No. 84113/1987.)

The second one is a particular resin formed by emulsion polymerizationof a polyfunctional monomer having at least two ethylenic unsaturatedbonds (which differ in copolymerization reactivity) and avinyl-polymerizable monomer reactive only with one of the unsaturatedbonds of the polyfunctional monomer, with at least one of theunsaturated bonds of the crosslinkable monomer remaining intact. (SeeJapanese Patent Laid-open No. 246916/1987.)

The former particulate resin is intended for incorporation into asolvent-based paint composition which forms a coating film havingsuperior physical properties such as hardness, abrasion resistance,tensile strength, and heat resistance. The latter particulate resin isintended for immobilization of a functional polymer or dissimilarsubstance on the particle surface or incorporating into a solvent-basedpaint composition for the improvement of application property andstorage ability. Consequently, none of these particulate resins has beenused as a shrinkage reducing agent for BMS and SMC.

SUMMARY OF THE INVENTION

The present invention was completed to eliminate the above-mentioneddisadvantages. It is an object of the present invention to provide a newreactive particulate resin that can be incorporated into a resincomposition for the reduction of shrinkage. It is another object of thepresent invention to provide a method for producing the reactiveparticulate resin.

The present invention is based on a new particulate resin ofthree-dimensional structure which has crosslinkable reactive groups onthe particle surface. In addition, the present invention is based on thefinding that the above-mentioned problems are solved if the resincomposition is incorporated with the particulate resin for the reductionof shrinkage.

Incidentally, "%" and "parts" mean "wt %" and "parts by weight",respectively, throughout the specification and the claims.

According to the invention, we provide a reactive particulate resin eachparticle of which comprises a core of three-dimensionally crosslinkedresin having a degree of crosslinking from 0.05 to 2.0 mmol/g, and ashell formed thereon having a radical-polymerizable ethylenicunsaturated bond. The shell is formed by polymerization of one or morepolyfunctional monomers (A) and one or more non-aromaticradical-polymerizable monomers (B). The polyfunctional monomer (A)having in the molecule at least one species selected from the groupconsisting of 1-monosubstituted and 1,1-disubstitutedradical-polymerizable ethylenic unsaturated bonds (a) and also having inthe molecule at least one of at least one species selected from thegroup consisting of 1,2-disubstituted, 1,1,2-trisubstituted, and1,1,2,2-tetrasubstituted radical-polymerizable ethylenic unsaturatedbonds (b).

The core particle can be formed from a vinyl-polymerizable monomer and acrosslinkable monomer having at least two copolymerizable ethylenicunsaturated bonds by emulsion polymerization, with the amount of themonomers being such that the core particle has a degree of crosslinkingfrom 0.05 to 2.0 mmol/g.

The core particle can also be formed by emulsion polymerization from amixture composed of polyfunctional monomer (A), a radical-polymerizablemonomer (B), and a polyfunctional monomer (C) having in the molecule atleast two of at least one species of 1-monosubstituted and1,1-disubstituted radical-polymerizable ethylenic unsaturated bonds.

The reactive particulate resin of the present invention is produced by amethod which comprises a first step of synthesizing particle cores ofthree-dimensionally crosslinked resin having a degree of crosslinking inthe range from 0.05 to 2.0 mmol/g, and a second step of forming on thesurface of said particle core a shell having a radical-polymerizableethylenic unsaturated bond, by polymerization of one or morepolyfunctional monomers (A) and one or more non-aromaticradical-polymerizable monomers (B), said polyfunctional monomer (A)having in the molecule at least one species selected from the groupconsisting of 1-monosubstituted and 1,1-disubstituted radicalpolymerizable ethylenic unsaturated bonds (a) and also having in themolecule at least one of at least one species selected from the groupconsisting of 1,2-disubstituted, 1,1,2-trisubstituted, and1,1,2,2-tetrasubstituted radical-polymerizable ethylenic unsaturatedbonds (b).

The reactive particulate resin pertaining to the present invention isunique in that the ethylenic unsaturated bond (b) in the shell remainsuncopolymerized. When the particulate resin is incorporated into amonomer or thermosetting resin having at least one ethylenic unsaturatedbond copolymerizable with the ethylenic unsaturated bond (b), theresulting dispersion (in monomer) or thermosetting resin compositioncures through copolymerization of the ethylenic unsaturated bond (b)with an ethylenic unsaturated bond in the monomer or thermosettingresin. This copolymerization permits the chemical bonding between thereactive particulate resin and the matrix. Thus the particulate resinreduces molding shrinkage and the chemical bonding eliminates the lightscattering at the interface between the reactive particulate resin andthe matrix. (The scattered light impairs the translucent appearance ofthe molded product.) Moreover, the chemical bonding between the reactiveparticulate resin and the matrix greatly improves the heat resistanceand water resistance of the molded product.

The reactive particulate resin of the present invention minimizes themolding shrinkage of a resin and gives rise to a molded product having agood translucent appearance, good durability, and high dimensionalstability. When incorporated into a thermosetting resin or monomer, thereactive particulate resin forms a stable resin composition ordispersion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a molded product in Example 7 ofthe present invention.

FIG. 2 is a vertical sectional view showing the structure of a hot watertest apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(i) Reactive Particulate Resin

The preferable reactive particulate resin of the present invention isunique in that each particle is composed of a core and a shell formedthereon. The shell has radical-polymerizable ethylenic unsaturatedbonds. The core is made of a three-dimensionally crosslinked resinhaving a degree of cross-linking in the range from 0.05 to 2.0 mmol/g.The shell is formed by polymerization of one or more polyfunctionalmonomers (A) and one or more polymerizable monomers (B). Thepolyfunctional monomer (A) has in the molecule an ethylenic unsaturatedbond (a) capable of holopolymerization and an ethylenic unsaturated bond(b) incapable of either homopolymerization or copolymerization with saidethylenic unsaturated bond (a). The polymerizable bond (B) has anethylenic unsaturated bond (a) but substantially incapable ofcopolymerization with said ethylenic unsaturated bond (b). To be morespecific, the functional monmer (A) has at least one species of1-monosubstituted and 1,1-disubstituted radical-polymerizable ethyelnicunsaturated bonds (a) and at least one of at least one species of1,2-disubstituted, 1,1,2-trisubstituted, and 1,1,2,2-tetrasubstitutedradical-polymerizable ethyelnic unsaturated bonds (b). The ethyelnicunsaturated bond (a) is capable of homopolymerization, but the ethylenicunsatruated bond (b) is substantially incapable of eitherhomopolymerization or copolymerization with said ethyelnic unsaturatedbond (a). The non-aromatic radical-polymerization monomer (B) has anethylenic unsaturated bond capable of copolymerization with saidethylenic unsaturated bond (a) but substantially incapable ofcopolymerization with said ethylenic unsaturated bond (b).

The reactive particulate resin of the present invention is composed ofthe core and shell, with teh core/shell ratio being in the range from10/90 to 99/1 (by weight). With a core/shell ratio smaller than 10/90,the particulate resin gives rise to a molded product whihc is poor indurability. With a core/shell ratio greater than 99/1, the particulateresin is poor in dispersability in the resin composition or dispersion.A desired core/shell ratio rnages from 40/60 to 80/20.

The reactive particulate resin of the present invention should have anaverage particle diameter in the range from 0.01 to 5 μm. With aparticle diameter smaller than 0.01 μm, the particulate resin gives riseto a molded product which is poor in dimensional stabiliyt. With aparticle diameter greater than 5 μm, the particulate resin gives rise toa molded product which is poor in transluecent appearance. A desiredaverage particle diaemter is in the range from 0.05 to 2 μm.

The shell should have an adequate refractive index which is not greaterby 0.05 than that of the resin (matrix) into which the reactiveparticulate resin is incorporated.

(ii) Production of the Reactive Particulate Resin

The reactive particulate resin of the present invention is produced inthe folloiwng manner.

(ii-a) The First Step

The first step involves the synthesis of the core from athree-dimensionally corsslinked resin. This is accomplished by emulsionpolymerization of a vinyl-polymerizable monomer and a crosslinkablemonomer having at least two copolymerizable ethylenic unsaturated bonds.The emulsion polymerization is carried out until the degree ofcroslinking reaches 0.05-2.0 mmol/g, preferably 0.2-1.0 mmol/g.

The vinyl-polymerizable monomer is not specifically limioted. Itsexamples include the following. (Meth)acrylates such as methyl acrylate,methyl methacrylate, ethyl acrylate, ethyl methacyrlate, n-butylacrylate, n-butyl methacrylate, isobutyl acrylate, 2-ethylhexylacrylate, laruyl methacrylate, and phenyl acylrate. Polymerizablearomatic ompounds such as styrnee, α-methylstyrene, vinyl ketone,t-butylstyrene, parachlorostyrene, and vinyl naphthalene. Carboxylgorup-containnig monomers such as acrylic acid, methacrylic acid,crotonic acid, itaconic acid, maleic acid, and fumaric acid. Hydroxylgroup-containing monomers such as 2-hydroxyethyl acrylate,2-hydroxyethyl methacyrlate, hydroxypropyl arylate, hydroxypropylmethacrylate, hydroxybutyl acryate, hydroxybutyl methacryatel, allylalcohol, and methallyl alcohol. Nitrogen-containing alkyl(meth)acrylates such as dimethylaminoethyl acrylate, dimethylaminoethylmethacrylate, dimethylaminopropyl acrylate, dimethylaminopropylmethacrylate, and dimethylaminopropyl methacrylimide. Polymerizableamides such as acrylamide, methacrylamide, N-metholacrylamide, andN-methoxymethylacrylamide. Polymerizable nitriles such as acrylonitrileand methacrylonitrile. Vinyl halides such as vinyl chloride, vinylbromide, and vinyl fluoride. α-Olefines such as ethylene and propylene.Vinyl compounds such as vinyl acetate and vinyl propionate. Dienecompounds such as butadiene and isoprene.

The crosslinkable monomer is not specifically limited so long as it hasin the molecule two or more radical-polymerizable ethylenic unsaturatedbonds. Its examples include the following. Polymerizable unsaturatedmonocarboxylic ester of polyhydric alcohol such as ethylene glycoldiacrylate, ethylene glycol dimethacrylate, triethylene glycoldimethacrylate, tetraethylene glycol dimethacrylate, 1,3-butylene glycoldimethacrylate, trimethylolpropane triacrylate, trimethylolpropanetrimethlacrylate, 1,4-butanediol diacrylate, neopentyl glycoldiacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol diacrylate,1,6-hexanediol methacrylate, pentaerythritol diacrylate, pentaerythritoldimethacrylate, pentaerythritol triacrylate, pentaerythritoltrimethacrylate, pentaerythritol tetraacrylate, pentaerythritoltetramethacrylate, glycerol diacrylate, glycerol dimethacrylate,glycerol acryloxydimethacrylate, 1,1,1-trishydroxylmethylethanediacrylate, 1,1,1-trihydroxymethylethane dimethacrylate,1,1,1-trishydroxymethylethane triacrylate, 1,1,1-trishydroxymethylethanetrimethacrylate, 1,1,1-trishydroxymethylpropane diacrylate, and1,1,1-trihydroxymethylpropane dimethacrylate. Polymerizable unsaturatedalcohol ester of polybasic acid such as diallyl terephthalate, diallylphthalate, and triallyl trimellitate. Aromatic compound havnig two ormore substituent vinyl groups such as divinylbenzene. Addition compoundof a monomer having an epoxy group-containing ethylenic unsaturated bondand a monomer having a carboxyl group-containing ehtylenic unsaturatedbond, such as a reaction product of glycidyl acylrate or glycidylmethacrylate and acrylic acid or methacrylic acid.

In the case where the emulsion polymerization employs an emulsifier, theamount of the emulsifier should be 0.1-20 parts, preferably 2-10 parts,for 100 parts of the total amount of the monomers. There are norestrictuions on the kind of the emulsifier. It includes anionicsurfactants, cationic surfactants, amphoteric surfactants, nonionicsurfactants, and reactive and non-reactive surfactants. Examples of thesurfactants are listed below. Anionic surfactants such as fatty acidsopa, higher alcohol sulfate ester, alkylbenzenesulfone, anddioctylsulfosuccinate. They are commerically available under the tradenames of "Latemul S-120", "Latemul S-180", and "Latemul S-180A" (fromKao Corporation); "Newfrontier A229E" and "Aquaron HS-10" (from Dai-ichiKogyo Seiyaku Co., Ltd.); "Eliminol JS-2" and "Eliminol SSS" (from SanyoChemical Industries, Ltd.); "RA-1022", "RA-1024", "RA-421", "RA-423",and "Antox-MS-2N(7)" (from Nippon Nyukazai Co., Ltd.); and "SX-1154","SX-1159", and "SX-1163" (fro Asahi Denka Kogyo K.K.). Nonionicsurfactants such as polyethylene glycol alkyl ether, polyethyleneglocyol alkylphenyl ether, polyethylene glycol fatty acid ester,polypropylene glycol, polyethylene glycol ester, and polyoxyethylenesorbitan fatty acid ester. Commercial reactive nonionic emulsifiers suchas "Newfrontier N-177E" "Aquaron RN-20" (From Dai-ichi Kogyo SeiyakuCo., Ltd.); "RMA-862", "RA-951", "RA-953", "RA-954", "RA-955", "RA-957",and "RA-958" (from Nippon Nyukazai Co., Ltd.); "SX-1151", "SX-1152","SX-1156", and "SX-1157" (from Asahi Denka Kogyo K.K.). Commercialreactive cationic emulsifiers such as "Laetmul K-180" (from KaoCorporation); and "RF-755" and "RF-756" (from Nippon Nyukazai Co.,Ltd.). Preferred emulsifiers are reactive emulsifiers andpolyester-based emulsifiers having amphoteric ionic groups. (SeeJapanese Patent Laid-open Nos. 141727/1981 and 34725/1981.)

The method for preparing the core particules is not limited to the onementioned above. Othe methods include the well-known suspensionpolymerization, dispersion polymerization, and method for producingartificial latex. In addition, the crosslinking may be accomplished byaddition reaction and condensation reaction as well as radicalpolymerization. These reactions involve the combination of functionalgroups, suich as (carboxylic acid+amino group)/epoxy group, (hydroxylgroup+amino group)/isocyanate, (carboxylic acid+hydroxyl group/melamine,and mino group/active ester group.

The core particules can also be fromed by emulsion polymerization of amixture of the above-mentioned polyfunctional monomer (A), theabove-mentioned radical-polymerizable monomer (B), and a polyfunctionalmonomer (C) which has in the molecule at least two fo 1-monosubstiuttedradical-polymerizable ethylenic unsaturated bonds or 1,1-disubstitutedradical-polymerizable ethylenic unsaturated bonds or both.

The polymerization reaction (as the first step) may be carried out inthe presence of a radical polymerization initiator, if necessary. Thereare no restrictions on the kind of the initiator. Common exmaples of theinitiator are listed below. Solvent-soluble peroxides such as benzoylperoxide, parachlorobenzoyl peroxide, lauryl peroxide, and t-butylperbenzoate. Water-soluble peroxides such as potassium persulfate andammonium persulfate. Solvent-soluble azo compounds such asazobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), and2,2'-azobis(2,4-dimethylvaleronitrile). Water-soluble azo compounds suchas anionic azobiscyanovaleric acid and cationic2,2'-azobis(2-amidinopropane)hydrochloride.

(ii-b) The Second Step

The second step involves the formation of the shell. It is accomplishedby adding dropwise to the aqueous dispersion of the above-mentioned coreparticles a monomer mixture of one or more of the above-mentionedpolyfunctional monomer (A) and one or more of the above-mentionedpolymerizable monomer (B) and a solution of the initiator. Thepolyfunctional monomer (A) has in the molecule at least one speciesselected from 1-monosubstituted and 1,1-disubstitutedradical-polymerizable ethylenic unsaturated bonds (a) and at least oneof at least one species selected from 1,2-disubstituted,1,1,2-trisubstituted, and 1,1,2,2-tetrasubstituted radical-polymerizableethylenic unsaturated bonds (b), as mentioned above.

The polyfunctional monomer (A) is prepared by reacting the compoundhaving the ethylenic unsaturated bond (a) with the compound having theethylenic unsaturated bond (b), of which functional groups are bondableto each other. The reactions usable for the bonding of the functionalgroups are reactions known to a person skilled in the art, including areaction of a carboxylic anhydride group with a hydroxyl group,esterification of a carboxylic group with a hydroxyl group, a reactionof an isocyanate group with a group containing active hydrogen such ashydroxyl group and a thiol group, a reaction of a carboxylic halidegroup with a group containing active hydrogen such as a hydroxyl groupand a thiol group, a reaction of an epoxy group with a carboxyl group.The compound having an ethylenic unsaturated bond (a) for preparing thepolyfunctional monomer (A) is preferably (meth)acryl compound. Theexamples of the compound include (meth)acrylate monomer having a hydroxygroup such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl acrylate,etc.; (meth)acrylic acid monomer; (meth)acrylic halide monomer such as(meth)acrylic chloride; (meth)acrylate monomer having an epoxy groupsuch as glycidyl(meth)acrylate, "CYCLOMER M-100" and "A-200" produced byDAICEL Co., Ltd.; (meth)acrylate monomer having an isocyanate group suchas 2-isocyanate ethyl(meth)acrylate, etc. The examples of the compoundhaving an ethylenic unsaturated bond (b) include; as 1,2-disubstitutedcompound, maleic anhydride, maleic acid, fumaric acid, glutaconic acid,mono alkyl maleate, mono alkyl fumarate, β-chloro acrylic acid,(iso)crotonic acid, crotyl alcohol, crotonaldehyde; as1,1,2-trisubstituted compound, angelic acid, tiglic acid, α-ethylcrotonic acid, α-chloro crotonic acid, β-chloro crotonic acid, α-chloroisocrotonic acid, β-chloro isocrotonic acid, citraconic acid, citraconicanhydride, mesaconic acid, mono alkyl mesaconate, chloro maleic acid,mono alkyl chloro maleate, chloro fumaric acid, mono alkyl chlorofumarate, aconitic acid and mono alkyl aconitate; as1,1,2,2-tetrasubstituted compound, teraconic acid and mono alkylteraconate.

The preferable polyfunctional monomer (A) is a monomer which is selectedfrom the group consisting of a reaction product of maleic anhydride and2-hydroxyethyl (meth)acrylate, a reaction product of monobutyl maleateand glycidyl (meth)acrylate, a reaction product of (meth)acrylicchloride and crotyl alcohol, a reaction product of 2-hydroxy-ethyl(meth)acrylate and citraconic anhydride, etc.

The non-aromatic radical-polymerizable monomer (B) that can be used inthe second step includes those which are exemplified as thevinyl-polymerizable monomer that can be used in the first step.Preferred examples include (meth)acrylate monomers such as methylacrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,n-buty acrylate, n-butyl methacrylate, isobutyl acrylate, 2-ethylhexylacrylate, lauryl methacrylate, and phenyl acrylate.

The polyfunctional monomer (A) used in the second step should accountfor 1-50% in the total monomer that forms the shell. With an amount lessthan 1%, the polyfunctional monomer (A) does not form a sufficientlystrong interface between the fine particles and the resin, with theresult that the molded product is poor in durability. With an amount inexcess of 50%, the polyfunctional monomer (A) leads to a molded productwhich is poor in dimension stability. A desired amount of thepolyfunctional monomer (A) ranges from 5% to 40%.

The polymerization reaction in the second step may employ an emulsifier,if necessary. The amount and kind of the emulsifier are as mentionedabove in connection with the first step.

Usually, the polymerization reaction in the second step is also carriedout in the presence of a radical polymerization initiator. There are norestrictions on the kind of initiator. Those exemplified in theexplanation for the first step may be used.

The reactive particulate resin of the present invention may be availablein the form of dispersion (1-40 parts) in a monomer (alone or incombination with other monomers) which has at least one ethylenicunsaturated bond capable of copolymerization with the above-mentionedethylenic unsaturated bond (b).

(iii) Thermosetting Resin Composition for Thermoforming

The above-mentioned reactive particulate resin is incorporated into athermosetting resin for the reduction of molding shrinkage. Theresulting thermosetting resin composition is used for thermoforming. Thethermoforming resin composition is composed of a thermosetting resin, aninorganic filler, and a reactive particulate resin.

The thermosetting resin as one of the constituents of the resincomposition includes, for example, unsaturated polyester resins,thermosetting acrylic resins, and thermosetting vinyl ester resins.

The inorganic filler as one of the constituents of the resin compositionincludes, for example, glass powder, aluminum hydroxide, and calciumsilicate. (Glass powder has a refractive index of 1.46-1.60 and anaverage particle diameter of 1-300 μm, preferably 20-100 μm. Aluminumhydroxide has a refractive index of 1.57.) They may be used alone or incombination with one another. The inorganic filler may besurface-treated with a silane coupling agent to impart the translucentmarble-like appearance to the molded product and to improve the hotwater resistance of the molded product. Preferred inorganic fillers areglass powder (having the above-mentioned refractive index) and aluminumhydroxide and a mixture thereof.

The reactive particulate resin as one of the constituents of the resincomposition functions to reduce the molding shrinkage. It should have anaverage particle diameter of 0.01-5 μm, preferably 0.02-1 μm, and arefractive index of 1.46-1.60.

For the resin composition to give rise to a translucent molded product,it is necessary that the thermosetting resin, inorganic filler, andreactive particulate resin have refractive indexes which are as close toone another as possible, so that the light scattering is minimized atthe interface between the resin and the filler and between the resin andthe reactive particulate resin. Since the thermosetting resin usuallyhas a refractive index of 1.48-1.57, the refractive index of theinorganic filler and reactive particulate resin should be in the rangefrom 1.46 to 1.60. With a refractive index outside this range, theinorganic filler and reactive particulate resin will bring aboutconsiderable light scattering at their interface and hence make themolded product poor in translucent appearance. It is desirable that therefractive index of the inorganic filler and reactive particulate resinshould be ±0.05 of that of the thermosetting resin.

A detailed description will be given below of the constituents andmolding method of the resin composition pertaining to the presentinvention.

(A) Thermosetting Resin

One of the thermosetting resins that can be used in the presentinvention is an unsaturated polyester resin which is known well. Itcomes in the form of syrup which is a solution of an unsaturatedpolyester prepolymer in an ethylenic unsaturated monomer. Theunsaturated polyester prepolymer is derived by polycondensation of atleast one polybasic carboxylic acid (including an ethylenic unsaturatedpolycarboxylic acid) and at least one diol. Examples of the ethylenicunsaturated polycarboxylic acid include maleic acid, maleic anhydride,fumaric acid, itaconic acid, tetrahydrophthalic anhydride, and3,6-endomethylenetetrahydrophthalic anhydride. The polybasic carboxylicacid to be used in combination with them includes, for example, phthalicanhydride, isophthalic acid, terephthalic acid, tetrachlorophthalicanhydride, adipic acid, sebacic acid, and succinic acid. Examples of thediol include ethylene glycol, diethylene glycol, triethylene glycol,1,2-propylene glycol, butanediol, neopentyl glycol, hydrogenatedbisphenol A, 2,2-bis(4-oxyethoxyphenol)propane, and2,2-bis(4-oxypropoxyphenol)propane.

The unsaturated polyester prepolymer may be replaced by the one such asdiallyl phthalate (DAP) which is derived from a polycarboxylic acid andan ethylenic unsaturated alcohol.

The ethylenic unsaturated monomer includes liquid monomers capable ofradical polymerization which may be used alone or in combination withone another. The monomer should be combined with a proper polyesterprepolymer which forms a uniform solution. Preferred examples of themonomer include aromatic vinyl such as styrene, vinyltoluene,α-methylstyrene, and divinylbenzene, and ethylenic unsaturated esterssuch as ethyl acrylate, methyl methacrylate, diallyl phthalate, andtriallyl cyanurate. These examples are not limitative.

The mixing ratio of the unsaturated polyester prepolymer to ethylenicunsaturated monomer should be from 70:30 to 45:55, preferably from 65:35to 55:45 (by weight). The prepolymer solution in the monomer shouldpreferably have a viscosity of 50-8000 cP (25° C.).

Another example of the thermosetting resin is a known thermosettingacrylic resin. It is produced by the copolymerization of an acrylateester or methacrylate ester with another monomer, which is followed bythe introduction of a carboxyl group, epoxy group, hydroxyl group, amidogroup, amino group, or vinyl group (having an ethylenic double bond). Itis capable of self-cure in the presence of a catalyst, or it is cured bya crosslinking agent.

Further another example of the thermosetting resin is a vinyl esterresin which consists of ester main chains or ether main chains andterminal vinyl groups. Usually, it is an epoxy acrylate diluted with apolymerizable monomer (such as styrene). The epoxy acrylate is formed byreaction of an epoxy resin (having the bisphenol A skeleton) with anunsaturated monobasic acid such as acrylic acid and methacrylic acid.

(B) Inorganic Filler

An example of the inorganic filler is glass powder. For the moldedproduct to have a translucent marble-like appearance, the glass powdershould have a refractive index of 1.46-1.60, preferably within the plusor minus 0.05 of that of the thermosetting resin. In addition, it shouldhave an average particle diameter of 1-300 μm. The glass powder shouldbe prepared from borosilicate glass having the following composition.SiO₂ : 40-65%, B₂ O₃ : 2-30%, alkali metal oxide; 2-25%, alkaline earthmetal oxide or ZnO: 5-30%, Al₂ O₃ : 0-25%, TiO₂ : 0-10%, and ZrO₂ :0-10%.

Another example of the inorganic filler is aluminum hydroxide. As in thecase of glass powder, it should preferably have a particle diameter inthe range of 1 to 300 μm, so that the resulting molded product has atranslucent marble-like appearance. It is commercially available underthe trade name of "Higilite H-310" or "Higilite H-320" (from Showa DenkoK.K.). Aluminum hydroxide functions also as a flame retardant. A mixtureof aluminum hydroxide and glass powder can be used as the inorganicfiller.

The inorganic filler (such as glass powder and aluminum hydroxide) maybe used as such or after surface-treatment with a known silane couplingagent. A preferred silane coupling agent is a silane having in themolecule ethylenic unsaturated bonds and hydrolyzable groups. Examplesof such coupling agents include vinyltriethoxysilane,vinyltris-β-methoxyethoxysilane, andγ-methacryloxypropyltrimethoxysilane. They should be used in an amountof 0.01-2 parts for 100 parts of the inorganic filler.

(C) Reactive Particulate Resin

The reactive particulate resin as a constituent of the resin compositionshould have a degree of crosslinking and an average particle diameter asspecified above. The shell of the particle should have a refractiveindex which is within plus or minus 0.05 of that of the matrix resin andother constituents. A desired refractive index ranges from 1.46 to 1.60.

(D) Formulation of the Resin Composition

The resin composition of the present invention is composed of 100 partsof thermosetting resin, 100-400 parts of inorganic filler, and 5-30parts of the reactive particulate resin.

If the amount of inorganic filler is less than 100 parts, the resultingmolded product does not show the translucent marble-like appearance,lacking weightiness and texture. In addition, the molded product suffersfrom cracking at the molding time and is poor in heat resistance. If theamount of inorganic filler exceeds 400 parts, the resin compositionlacks fluidity necessary for molding and the resulting molded product ispoor in machinability. In other words, an excess amount of inorganicfiller aggravates the moldability of the resin composition and themechanical properties of the molded product.

If the amount of the reactive particulate resin is less than 5 parts,the resin composition is liable to cracking because the reactiveparticulate resin does not produce its effect of reducing the moldingshrinkage. An adequate amount should be selected so that the reactiveparticulate resin produces the desired effect. An amount more than 30parts is economically inadequate.

According to a preferred formulation, the resin composition is composedof 100 parts of thermosetting resin, 150-350 parts of inorganic filler,and 10-20 parts of the reactive particulate resin.

(E) Additional Components

The resin composition of the present invention may be incorporated, inaddition to the above-mentioned essential components, with optionalcomponents which are commonly used for thermosetting resin compositionsof this kind according to need. The optional components include fiberreinforcement, coloring agent, internal mold release, thickened, andwater retainer. Examples of the fiber reinforcement include glass fiber,aramid fiber, vinylon fiber, polyester fiber, and polyimide fiber, allof which have a fiber length of 0.5-50 mm. Examples of the coloringagent include organic and inorganic pigments and toners thereof.Examples of the internal mold release include metal soap (such as zincstearate and calcium stearate) and phosphate esters. Examples of thethickener include alkaline earth metal oxide or hydroxide such asmagnesium oxide and calcium hydroxide.

The thermosetting resin composition needs a catalyst for its curing. Thecatalyst includes organic peroxides such as benzoyl peroxide,parachlorobenozyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroylperoxide, acetyl peroxide, dicumyl peroxide,2,5-dimethyl-2,5-di(t-butylperoxy)-hexane, and t-butyl perbenozate. Theymay be used alone or in combination with one another. The amount of thecatalyst should preferably be 0.3-2.5% of the amount of the resin.

(F) Molding Method

The resin composition of the present invention has such a viscosity thatit can take the shape of sheet, lump, rod, and pellet. Therefore, it isused as a material for SMC and BMC to be formed into bathtubs, kitchencounters, washstands, bathroom panels, and table tops which need atranslucent appearance. This forming is accomplished by thermoforming aswell as pressure thermoforming. There are no restrictions on the formingconditions. The forming temperature ranges from 90° to 160° C. and theforming pressure ranges from 20 to 140 kg/cm².

EXAMPLES

The invention will be described in more detail with reference to thefollowing examples which are divided into three parts: (a) Production ofthe reactive particulate resin, (b) Production of molded products fromthe thermosetting resin composition, and (c) Test of molded products forquality.

(a) Reactive Particulate Resin

Manufacturing Example 1 Polyester-Type Amphoteric Emulsifier

In a glass reactor equipped with a thermometer, reflux condenser,nitrogen inlet, stirrer, and decanter were placed 134 parts ofbishydroxyethytaurine, 130 parts of neopentyl glycol, 236 parts ofazelaic acid, 186 parts of phthalic anhydride, and 27 parts of xylene.The reactants were heated with refluxing. The water formed by reactionwas removed by azeotropy with xylene. The temperature was graduallyraised to 190° C. over about 2 hours after the start of refluxing, andthe stirring and dehydration were continued until the acid value(equivalent to carboxylic acid) reached 145. The temperature was loweredto 140° C. To the reactor kept at this temperature was added dropwise314 parts of glycidyl ester of versatic acid "Cardura E10" (made byShell Chemical Company) over 30 minutes. Stirring was continued for 2hours before the completion of reaction. Thus there was obtained apolyester-type amphoteric emulsifier having an acid value of 59, ahydroxyl value of 90, and an average molecular weight of 1054.

Manufacturing Example 2 Polyfunctional Monomer

In a glass reactor equipped with a thermometer, reflux condenser, airinlet, and stirrer were placed 98 parts of maleic anhydride, 130 partsof 2-hydroxyethyl methacrylate, 57 parts of toluene, and 0.5 part ofp-methoxyphenol Reaction was carried out at 110° C. for 1 hour with airbubbling. The reaction liquid was cooled and freed of solvent underreduced pressure. Thus there was obtained a polyfunctional monomer (A)which has an ethylenic unsaturated bond derived from maleic acid and anethylenic unsaturated bond derived from methacrylic acid. (Theseradical-polymerizable ethylenic unsaturated bonds differ in reactivity.)

Manufacturing Example 3 Polyfunctional Monomer

In a glass reactor equipped with a thermometer, reflux condenser, airinlet, and stirrer were placed 172 parts of monobutyl maleate, 149 partsof glycidyl methacrylate, and 0.5 part of p-methoxyphenol. Reaction wascarried out at 160° C. for 1 hour with air bubbling, and the reactionliquid was cooled. Thus there was obtained a polyfunctional monomer (A)which has an ethylenic unsaturated bond derived from maleic acid and anethylenic unsaturated bond derived from methacrylic acid. (Theseradical-polymerizable ethylenic unsaturated bonds differ in reactivity.)

Manufacturing Example 4 Polyfunctional Monomer

In a glass reactor equipped with a thermometer, reflux condenser, airinlet, and stirrer were placed 72 parts of crotyl alcohol, 111 parts oftriethylamine and 280 parts of toluene, and the temperature was raisedto 50° C. To the reactor kept at this temperature was added dropwise asolution consisting of 100 parts of acrylic chloride and 100 parts oftoluene over 60 minutes. After the reaction liquid was kept at 50° C.for 30 minutes, 20 parts of ethanol was added and the reaction liquidwas further kept at 50° C. for 1 hour, then cooled. The precipitate wasfiltered off, and the solvent was removed under reduced pressure. Thusthere was obtained a polyfunctional monomer (A) which has an ethylenicunsaturated bond derived from acrylic chloride (1-mono substitutedcompound) and an ethylenic unsaturated bond derived from crotyl alcohol(1,2-di substituted compound). (These radical-polymerizable ethylenicunsaturated bonds differ in reactivity).

Manufacturing Example 5 Polyfunctional Monomer

In a glass reactor equipped with a thermometer, reflux condenser, airinlet, and stirrer were placed 112 parts of citraconic anhydride, 116parts of 2-hydroxyethyl acrylate, 57 parts of toluene and 0.5 part ofp-methoxyphenol. Reaction was carried out at 110° C. for 1 hour with airbubbling. Then, the reaction liquid was cooled and the solvent wasremoved under reduced pressure. Thus there was obtained a polyfunctionalmonomer (A) which has an ethylenic unsaturated bond derived from2-hydroxyethyl acrylate (1-mono substituted compound) and an ethylenicunsaturated bond derived from citraconic anhydride (1,1,2-trisubstitutedcompound). (These radical-polymerizable ethylenic unsaturated bondsdiffer in reactivity.)

EXAMPLE 1 Production of Particulate Resin by Two-Stage EmulsionPolymerization

In a glass reactor equipped with a thermometer, reflux condenser,nitrogen inlet, and stirrer were placed 213 parts of deionized water and5.5 parts of reactive emulsifier "Newfrontier A 229E" (made by Dai-ichiKogyo Seiyaku Co., Ltd.). The reactants were heated to 81°-85° C., withnitrogen bubbling. To the reactor were further added dropwise a monomermixture composed of 30 parts of styrene, 10 parts of n-butyl acrylate,and 10 parts of neopentylglycol dimethacrylate, and a half of aninitiator aqueous solution composed of 20 parts of deionized water, 1part of azobiscyanovaleric acid, and 0.64 part of dimethylethanolamine,over 30 minutes from separate dropping funnels. As the result of thefirst step, there were obtained crosslinked core particles.

To the reactor were added dropwise a monomer mixture composed of 15parts of polyfunctional monomer (A) obtained in Manufacturing Example 2,17.5 parts of methyl methacrylate, and 17.5 parts of n-butyl acrylate,and the remaining half of the initiator aqueous solution (mentionedabove), over 30 minutes from separate dropping funnels. After ageing for1 hour, the reaction liquid was cooled. Thus there was obtained thereactive particulate resin (1) having an average particle diameter of0.07 μm and a core/shell ratio of 5/5, with the shell containingethylenic unsaturated bonds.

EXAMPLE 2 Production of Particulate Resin by Two-Step EmulsionPolymerization

In a glass reactor equipped with a thermometer, reflux condenser,nitrogen inlet, and stirrer were placed 215 parts of deionized water, 10parts of the emulsifier obtained in Manufacturing Example 1, and 1 partof dimethylethanolamine. The reactants were heated to 81°-85° C., withnitrogen bubbling. To the reactor were further added dropwise a monomermixture composed of 35 parts of methyl methacrylate, 15 parts of n-butylacrylate, 15 parts of ethylene glycol dimethacrylate, and 5 parts ofpolyfunctional monomer (A) obtained in Manufacturing Example 2, and 70%of an initiator aqueous solution composed of 20 parts of deionizedwater, 1 part of azobiscyanovaleric acid, and 0.64 part ofdimethylethanolamine, over 40 minutes from separate dropping funnels. Asthe result of the first step, there were obtained crosslinked coreparticles.

To the reactor were added dropwise a monomer mixture composed of 10parts of polyfunctional monomer (A) obtained in Manufacturing Example 2,15 parts of methyl methacrylate, and 5 parts of benzyl methacrylate, andthe remaining 30% of the initiator aqueous solution (mentioned above),over 20 minutes from separate dropping funnels. After ageing for 1 hour,the reaction liquid was cooled. Thus there was obtained reactiveparticulate resin (2) having an average particle diameter of 0.11 μm anda core/shell ratio of 7/3, with the shell containing ethylenicunsaturated bonds.

EXAMPLE 3 Soap-Free Cationic Particles of Large Particle Diameter

In a glass reactor equipped with a thermometer, reflux condenser,nitrogen inlet, and stirrer was placed 109 parts of deionized water,which was heated to 75° C. To the reactor were added 5 parts of methylmethacrylate and an aqueous solution composed of 10 parts of deionizedwater and 0.5 part of 2,2'-azobis(2-aminopropane)hydrochloride "V-50"(made by Wako Junyaku Co., Ltd.), followed by reaction for 10 minutes.To the reactor was further added dropwise for 50 minutes a monomermixture composed of 40 parts of methyl methacrylate, 20 parts of n-butylacrylate, and 20 parts of 1,6-hexanediol dimethacrylate, followed byageing for 20 minutes. To the reactor was added dropwise over 10 minutesa monomer mixture composed of 10 parts of polyfunctional monomer (A)obtained in Manufacturing Example 3 and 10 parts of methyl methacrylate.After ageing for 1 hour, the reaction liquid was cooled. Thus there wasobtained a soap-free cationic reactive particulate resin (3) having anaverage particle diameter of 1.1 μm and a core/shell ratio of 8/2, withthe shell containing ethylenic unsaturated bonds.

EXAMPLE 4 Production of Melamine-Crosslinked Particles by Method forProducing Artificial Latex

In a glass reactor equipped with a thermometer, reflux condenser,nitrogen inlet, and stirrer were placed 91 parts of water-solubleacrylic resin "Coatax WE-804" (with 50% solids, made by TorayIndustries, Inc.), 100 parts of melamine resin "Uvan 22" (with 50%solids, made by Mitsui Toatsu Co., Ltd.), and 1.4 parts oftriethylamine. To the reactants was slowly added 308 parts of deionizedwater with stirring for emulsification. The solvent was removed underreduced pressure while deionized water was being replenished. Thereaction liquid was kept at 60° C. for 1 week and then cooled. Thisfirst step gave crosslinked core particles. The reaction liquid washeated to 81°-85° C. with nitrogen bubbling. To the reactor were addeddropwise over 15 minutes a monomer mixture composed of 8 parts ofpolyfunctional monomer (A) obtained in Manufacturing Example 2 and 2.5parts of methyl methacrylate, and an initiator aqueous solution composedof 20 parts of deionized water, 0.2 part of azobiscyanovaleric acid, and0.13 part of dimethylethanolamine, from separate dropping funnels. Afterageing for 1 hour, the reaction liquid was cooled. As the result oftwo-step emulsion polymerization, there was obtained a reactiveparticulate resin (4) having an average particle diameter of 0.12 μm anda core/shell ratio of 9/1, with the shell containing ethylenicunsaturated bonds.

EXAMPLE 5 Production of Particulate Resin by Two-Step EmulsionPolymerization

In a glass reactor equipped with a thermometer, reflux condenser,nitrogen inlet, and stirrer were placed 213 parts of deionized water and12.8 parts of reactive emulsifier "Eleminol JS2" (made by Sanyo ChemicalIndustries, Ltd.). The solution was heated to 81°-85° C. with nitrogenbubbling. After that, the same procedures as those of Example 1 werecarried out with the exception of using the polyfunctional monomer (A)which had been prepared in Manufacturing Example 4. Thus there wasobtained a reactive particulate resin (5) having an average particlediameter of 0.08 μm and a core/shell ratio of 5/5 with the shellcontaining ethylenic unsaturated bonds.

EXAMPLE 6 Production of Particulate Resin by Two-Step EmulsionPolymerization

The same procedures as those in Example 2 were carried out with theexception of using the polyfunctional monomer (A) which had beenprepared in Manufacturing Example 5. Thus there was obtained a reactiveparticulate resin (6) having an average particle diameter of 0.10 μm anda core/shell ratio of 7/3 with the shell containing ethylenicunsaturated bonds.

Comparative Example 1 Single-Layered Crosslinked Particles

In a glass reactor equipped with a thermometer, reflux condenser,nitrogen inlet, and stirrer were placed 215 parts of deionized water, 10parts of emulsifier obtained in Manufacturing Example 1, and 1 part ofdimethylethanolamine. The reactants were heated to 81°-85° C., withnitrogen bubbling. To the reactor were further added dropwise over 60minutes a monomer mixture composed of 60 parts of styrene and 40 partsof ethylene glycol dimethacrylate, and an initiator aqueous solutioncomposed of 20 parts of deionized water, 1 part of azobiscyanovalericacid, and 0.64 part of dimethylethanolamine, from separate droppingfunnels. After ageing for 1 hour, the reaction liquid was cooled. Thusthere was obtained a styrene-based single-layered cross-linkedparticulate resin (5) having an average particle diameter of 0.06 μm.

Comparative Example 2 Particles Having No Reactive Groups

In a glass reactor equipped with a thermometer, reflux condenser,nitrogen inlet, and stirrer were placed 213 parts of deionized water and5.5 parts of emulsifier "Eleminol JS2" (made by Sanyo ChemicalIndustries, Ltd.). The solution was heated to 81°-85° C. with nitrogenbubbling. To the reactor were added dropwise over 30 minutes a monomermixture composed of 30 parts of styrene, 10 parts of n-butyl acrylate,and 10 parts of neopentyl glycol methacrylate, and a half of aninitiator aqueous solution composed of 20 parts of deionized water, 1part of azobiscyanovaleric acid, and 0.64 part of dimethylethanolamine,from separate dropping funnels. This first step gave crosslinked coreparticles. To the reactor were further added dropwise over 30 minutes amonomer mixture composed of 32.5 parts of methyl methacrylate and 17.5parts of n-butyl acrylate, and the remaining half of the initiatoraqueous solution (mentioned above), from separated dropping funnels.After ageing for 1 hour, the reaction liquid was cooled. Thus there wasobtained a core/shell-type crosslinked particulate resin (6) having anaverage particle diameter of 0.06 μm and a core/shell ratio of 5/5, withthe shell having no ethylenic unsaturated bonds.

Comparative Example 3 Single-Layered Crosslinked Particles HavingReactive Groups

In a glass reactor equipped with a thermometer, reflux condenser,nitrogen inlet, and stirrer were placed 215 parts of deionized water, 10parts of emulsifier obtained in Manufacturing Example 1, and 1 part ofdimethylethanolamine. The reactants were heated to 81°-85° C., withnitrogen bubbling. To the reactor were further added dropwise over 60minutes a monomer mixture composed of 40 parts of methyl methacrylate,20 parts of n-butyl acrylate, 10 parts of ethylene glycoldimethacrylate, and 10 parts of polyfunctional monomer (A) obtained inManufacturing Example 2, and an initiator aqueous solution composed of20 parts of deionized water, 1 part of azobiscyanovaleric acid, and 0.64part of dimethylethanolamine from separate dropping funnels. Afterageing for 1 hour, the reaction liquid was cooled. Thus there wasobtained a single-layered particulate resin (7) having an averageparticle diameter of 0.09 μm and ethylenic unsaturated bonds.

(b) Thermosetting resin composition and molded product thereof

EXAMPLE 7

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7661" made by Japan U-Pica Co., Ltd.)    Glass powder treated with a silane coupling                                2500 g    agent ("M-27-S" having a refractive index of    1.548, made by Ferro Enamels (Japan) Limited.)    Reactive particulate resin (2)                                120 g    (having a refractive index of 1.53,    obtained in Example 2)    Magnesium oxide             10 g    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                150 g    Total                       3840 g    ______________________________________

(i) The above-mentioned components were mixed for 10 minutes in a5-liter kneader. The intimate mixture was wrapped in a polyethylene filmand then in an aluminum-deposited polyethylene terephthalate film. Thewrapped mixture was aged in a drying oven at 45° C. for 20 hours. Thusthere was obtained a thickened hard resin composition (1) for pressmolding.

(ii) After the removal of wrapping films, the resin composition (1) wascut into pieces of adequate size. A proper amount of the resincomposition was placed in a press molding die and press-molded for 5minutes at a molding temperature of 130° C. and a clamping pressure of60 kg/cm². Thus there was obtained a molded product (7) as shown in FIG.1 having the dimensions 260 mm length, 160 mm width and 10 mm thickness.This molded product (7) was free of cracking, sinkmarks, and warpage,and had good surface gloss and high clarity.

EXAMPLE 8

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7661" made by Japan U-Pica Co., Ltd.)    Aluminum hydroxide          2500 g    (having a refractive index of 1.567,    "Higilite H-320" made by Showa Denko K.K.)    Reactive particulate resin (2)                                120 g    (having a refractive index of 1.53,    obtained in Example 2)    Magnesium oxide             10 g    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                150 g    Total                       3840 g    ______________________________________

The above-mentioned components were mixed and aged in the same manner asin step (i) of Example 7 to give a resin composition (2) for pressmolding. The resin composition was made into a molded product (2) bypress molding in the same manner as in step (ii) of Example 7. Themolded product (2) was free of cracking, sinkmarks, and warpage, and hadgood surface gloss and clarity. It was slightly inferior to the moldedproduct (1) in clarity.

EXAMPLE 9

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7520" made by Japan U-Pica Co., Ltd.)    Aluminum hydroxide          1500 g    (having a refractive index of 1.567,    "Higilite H-320", made by Showa Denko K.K.)    Reactive particulate resin (1)                                150 g    (having a refractive index of 1.48,    obtained in Example 1)    Magnesium oxide             10 g    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                400 g    Total                       3120 g    ______________________________________

(i) The above-mentioned components (excluding chopped strand gloss) weremixed for 5 minutes in a 5-liter container using a dissolver, to give anSMC premix. This premix was cast and spread on a polypropylene film togive a 2-mm thick premix sheet. This premix sheet was cut in half at itscenter. The first half of the premix sheet was placed flat, with thepremix surface up. On the premix surface was uniformly spread 400 g ofchopped strand gloss. The second half of the premix sheet was placed,with the premix surface down, on the first half of the premix sheet.Thus there was obtained a layered premix sheet, with gloss fiberinterposed between them. The layered premix sheet was passed through atwo-roll (with a 4-mm clearance) three times so that the glass fiber iscompletely impregnated with the premix. The premix sheet was tightlywrapped in an aluminum-deposited polyethylene terephthalate film andthen aged in a drying oven at 45° C. for 20 hours. Thus there wasobtained a thickened hard resin composition (3) for press molding.

(ii) After the removal of wrapping films, the resin composition (3) wascut into pieces of adequate size. With the polypropylene films removedfrom both sides of the premix sheet, a proper amount of the resincomposition was placed in a press molding die and press-molded for 5minutes at a molding temperature of 130° C. and a clamping pressure of60 kg/cm². Thus there was obtained a molded product (3) as shown inFIG. 1. This molded product (3) was free of cracking, sinkmarks, andwarpage, and had good surface gloss and as high clarity as the moldedproduct (2).

EXAMPLE 10

    ______________________________________    Vinyl ester resin           1000 g    ("Ripoxy RP-30" made by Showa Highpolymer    Co., Ltd.)    Glass powder treated with a silane coupling                                2500 g    agent ("M-27-S" having a refractive index of    1.548, made by Ferro Enamels (Japan) Limited.)    Reactive particulate resin (1)                                120 g    (having a refractive index of 1.48,    obtained in Example 1)    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                150 g    Total                       3830 g    ______________________________________

(i) The above-mentioned components were mixed for 10 minutes in a5-liter kneader. The intimate mixture was used as such as a resincomposition (4) for press molding.

(ii) The resin composition (4) was press-molded in the same manner as instep (ii) of Example 7, to give a molded product (4). This moldedproduct (4) was free of cracking, sinkmarks, and warpage, and had goodsurface gloss and high clarity.

EXAMPLE 11

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7660" made by Japan U-Pica Co., Ltd.)    Trimethylolpropane methacrylate                                300 g    Aluminum hydroxide          3000 g    (having a refractive index of 1.567,    "Higilite H-320", made by Showa Denko K.K.)    Reactive particulate resin (3)                                250 g    (having a refractive index of 1.49,    obtained in Example 3)    Zinc stearate               50 g    t-Butyl peroctoate          15 g    Chopped strand glass (13 mm long)                                250 g    Total                       4865 g    ______________________________________

The above-mentioned components were mixed in the same manner as in step(i) of Example 10 to give a resin composition (5) for press molding. Theresin composition was press-molded into a molded product (5) in the samemanner as in step (ii) of Example 7. This molded product (5) was free ofwarpage and had good surface gloss and high clarity, although it hadslight cracking at its corners.

EXAMPLE 12

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7661" made by Japan U-Pica Co., Ltd.)    Glass powder treated with a silane coupling                                2500 g    agent ("M-27-S" having a refractive index of    1.548, made by Ferro Enamels (Japan) Limited.)    Reacive particulate resin (4)                                150 g    (having a refractive index of 1.51,    obtained in Example 4)    Magnesium Oxide             10 g    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                150 g    Total                       3870 g    ______________________________________

Unsaturated polyester resin and the reactive particulate resin (4)obtained in Example 4 were mixed for 5 minutes in a 3-liter containerusing a dissolver, thus causing the reactive particulate resin (4) to bedispersed in the unsaturated polyester resin.

The dispersion obtained and the rest of the above-mentioned componentswere mixed in the same manner as in step (i) of Example 9 to give aresin composition (6) for press molding. The resin composition (6) waspress-molded into a molded product (6) in the same manner as in step(ii) of Example 9.

This molded product (6) was free of cracking, sinkmarks, and warpage,and had such good surface gloss and high clarity as the molded product(1).

EXAMPLE 13

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7661" made by Japan U-Pica Co., Ltd.)    Glass powder treated with a silane coupling                                2500 g    agent ("M-27-S" having a refractive index of    1.548, made by Ferro Enamels (Japan) Limited.)    Reacive particulate resin (5)                                150 g    (having a refractive index of 1.52,    obtained in Example 5)    Magnesium Oxide             10 g    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                150 g    Total                       3870 g    ______________________________________

The above-mentioned components were mixed in the same manner as in step(i) of Example 9 to give a resin composition (7) for press molding. Theresin composition (7) was press-molded into a molded product (7) in thesame manner as in step (ii) of Example 9.

This molded product (7) was free of cracking, sinkmarks, and warpage,and had such good surface gloss and high clarity as the molded product(1).

EXAMPLE 14

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7661" made by Japan U-Pica Co., Ltd.)    Glass powder treated with a silane coupling                                2500 g    agent ("M-27-S" having a refractive index of    1.548, made by Ferro Enamels (Japan) Limited.)    Reacive particulate resin (6)                                150 g    (having a refractive index of 1.50,    obtained in Example 6)    Magnesium Oxide             10 g    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                150 g    Total                       3870 g    ______________________________________

The above-mentioned components were mixed in the same manner as in step(i) of Example 9 to give a resin composition (8) for press molding. Theresin composition (8) was press-molded into a molded product (8) in thesame manner as in step (ii) of Example 9.

This molded product (8) was free of cracking, sinkmarks, and warpage,and had such good surface gloss and high clarity as the molded product(1).

Comparative Example 4

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7661" made by Japan U-Pica Co., Ltd.)    Glass powder treated with a silane coupling                                2500 g    agent ("M-27-S" having a refractive index of    1.548, made by Ferro Enamels (Japan) Limited.)    Shrinkage reducing agent (in liquid form)                                300 g    (polystyrene dissolved in styrene, "Polylite    PB-956" made by Dainippon Ink & Chemicals Inc.)    Magnesium oxide             10 g    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                150 g    Total                       4020 g    ______________________________________

The above-mentioned components were mixed in the same manner as in step(i) of Example 7 to give a resin composition (6) for press molding. Theresin composition (9) was press-molded into a molded product (9) in thesame manner as in step (ii) of Example 7. This molded product (9) wasfree of cracking, sinkmarks, and warpage, and had good surface gloss,but it looked turbid and opaque as a whole.

Comparative Example 5

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7661" made by Japan U-Pica Co, Ltd.)    Glass powder treated with a silane coupling                                2500 g    agent ("M-27-S" having a refractive index of    1.548, made by Ferro Enamels (Japan) Limited.)    Magnesium oxide             10 g    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                150 g    Total                       3720 g    ______________________________________

The above-mentioned components were mixed in the same manner as in step(i) of Example 7 to give a resin composition (10) for press molding. Theresin composition (10) was press-molded into a molded product (10) inthe same manner as in step (ii) of Example 7. This molded product (10)was as clear as the molded product (1) but suffered from cracking andwas poor in surface gloss.

Comparative Example 6

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7661" made by Japan U-Pica Co., Ltd.)    Aluminum hydroxide          2500 g    (having a refractive index of 1.567,    "Higilite H-320" made by Showa Denko K.K.)    Core/shell-type crosslinked particulate                                120 g    resin (6) (having a refractive index of 1.48,    obtained in Comparative Example 2)    Magnesium oxide             10 g    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                150 g    Total                       3840 g    ______________________________________

The above-mentioned components were mixed, followed by ageing, in thesame manner as in step (i) of Example 7 to give a resin composition (11)for press molding. The resin composition (11) was press-molded into amolded product (11) in the same manner as in step (ii) of Example 7.This molded product (11) was free of cracking, sinkmarks, and warpageand almost as good as the molded product (2) in surface gloss andclarity.

Comparative Example 7

    ______________________________________    Unsaturated polyester resin 1000 g    ("U-Pica 7520" made by Japan U-Pica Co., Ltd.)    Aluminum hydroxide          1500 g    (having a refractive index of 1.567,    "Higilite H-320" made by Showa Denko K.K.)    Styrene-based single-layered crosslinked                                200 g    particulate resin (5)    (Obtained in Comparative Example 1)    Magnesium oxide             10 g    Zinc stearate               50 g    t-Butyl peroctoate          10 g    Chopped strand glass (13 mm long)                                400 g    Total                       3170 g    ______________________________________

The above-mentioned components were mixed in the same manner as in step(i) of Example 9 to give a resin composition (12) for press molding. Theresin composition (12) was press-molded into a molded product (12) inthe same manner as in step (ii) of Example 9. This molded product (12)was free of cracking, sinkmarks, and warpage and had good surface gloss,but it looked turbid and opaque as a whole.

(c) Quality Test of Molded Products

Test 1 (Clarity and Moldability)

A test piece (50 mm square and 5 mm thick) was cut out of each moldedproduct. The test piece was placed on the white part of the hiding powerchart approved by the Japan Paint Inspecting Association, and the L_(w),a_(w), and b_(w) values of the test piece were measured using acolorimeter (Minolta CR-A10). The test piece was placed on the blackpart of the hiding power chart, and the L_(b), a_(b), and b_(b) valuesof the test piece were measured. The color difference ΔE_(wb) wascalculated from the following formula to judge the clarity of the testpiece. The greater the ΔE_(eb) value, the higher the clarity. ##EQU1##The test piece was also visually examined for moldability. The resultsof the test are shown in Table 1.

                  TABLE 1    ______________________________________    Test piece of Moldability Clarity    Molded poduct (Cracking)  ΔA.sub.wb                                       Visual    ______________________________________    Molded product (1)                  No cracking 7.0      very high    (Example 7)    Molded product (2)                  No cracking 4.8      very high    (Example 8)    Molded product (3)                  No cracking 4.5      very high    (Example 9)    Molded product (4)                  No cracking 6.7      very high    (Example 10)    Molded product (5)                  Slight cracking                              4.2      very high    (Example 11)  at corners    Molded product (6)                  No cracking 6.8      very high    (Example 12)    Molded product (7)                  No cracking 6.9      very high    (Example 13)    Molded product (8)                  No cracking 6.7      very high    (Example 14)    Molded product (9)                  No cracking 0.7      low    (Comp. Example 4)    Molded product (10)                  Severe cracking                              7.2      very high    (Comp. Example 5)    Molded product (11)                  No cracking 4.4      high    (Comp. Example 6)    Molded product (12)                  No cracking 0.4      low    (Comp. Example 7)    ______________________________________

It is noted from Table 1 that the molded products in Examples aresuperior in moldability and clarity to those in Comparative Examples.

Test 2 (Water Resistance)

A test piece (80 mm square and 5 mm thick) was cut out of each moldedproduct. The test piece was continuously exposed to hot water (97° C.)for 200 hours using a hot water test apparatus as shown in FIG. 2. Thetest apparatus is made up of a constant temperature bath (1) containinghot water (2), a thermometer (3), an opening for exposure to hot water(4), and a clamp (6) to fasten the test piece (5).

The clarity ΔE_(wb) of each test piece was measured in the same manneras mentioned above before and after the hot water treatment. (The testpiece was allowed to stand for 24 hours at room temperature beforemeasurement.) The hot water resistance of the test piece was judged fromthe change in clarity that occurred after the hot water treatment. Thetest piece was also visually examined for change in surface state. Theresults are shown in Table 2.

                  TABLE 2    ______________________________________                  Change in Change in                  ΔE.sub.wb after                            clarity by    Test piece of hot water hot water  Hot water    Molded poduct treatment treatment  resistant    ______________________________________    Molded product (1)                  18        very little                                       excellent    (Example 7)    Molded product (2)                  54        slightly   good    (Example 8)             whitened    Molded product (3)                  57        slightly   good    (Example 9)             whitened    Molded product (4)                  15        very little                                       excellent    (Example 10)    Molded product (5)                  51        slightly   good    (Example 11)            whitened    Molded product (6)                  23        very little                                       excellent    (Example 12)    Molded product (7)                  17        very little                                       excellent    (Example 13)    Molded product (8)                  19        very little                                       excellent    (Example 14)    Molded product (11)                  70        whitened,  poor                            opacified    ______________________________________     The change in ΔE.sub.wb after hot water treatment was calculated     from the following formula.

    (A-B)/A×100

(where A is ΔE_(wb) measured before hot water treatment, and B isΔE_(wb) measured after hot water treatment.)

It is noted from Table 2 than the molded products obtained in Examplesare superior in hot water resistance to that obtained in ComparativeExample.

Test 3 (Heat Resistance)

A test piece (50 mm square and 5 mm thick) was cut out of each moldedproduct. The test piece was heated in a drying oven at 200° C. for 10minutes, followed by cooling to room temperature. The test piece wasvisually examined for discoloration and change in clarity. The resultsare shown in Table 3.

                  TABLE 3    ______________________________________    Test piece of            Change in  Heat    Molded poduct Discoloration                             clarity    resistance    ______________________________________    Molded product (1)                  slightly   no change  good    (Example 7)   yellowed    Molded product (2)                  slightly   no change  good    (Example 8)   yellowed    Molded product (3)                  slightly   no change  good    (Example 9)   yellowed    Molded product (4)                  slightly   no change  good    (Example 10)  yellowed    Molded product (5)                  no change  no change  excellent    (Example 11)    Molded product (6)                  no change  no change  excellent    (Example 12)    Molded product (7)                  no change  no change  excellent    (Example 13)    Molded product (8)                  no change  no change  excellent    (Example 14)    Molded product (9)                  yellowed   whitened,  poor    (Comp. Example 4)        opacified    Molded product (11)                  slightly   whitened,  poor    (Comp. Example 6)                  yellowed   opacified    ______________________________________

It is noted from Table 3 that the molded products obtained in Examplesare superior in heat resistance to those obtained in ComparativeExamples.

Test 4 (Resistance to Live Cigarette)

A live cigarette was placed on the molded product for 10 minutes. Afterthe removal of the cigarette butt and ash, the surface of the moldedproduct was washed with acetone and visually checked for change. (Thecigarette used for this test was dried in a drying oven at 80° C. for 2hours.). The results are shown in Table 4.

                  TABLE 4    ______________________________________    Test piece of    Molded poduct Appearance       Rating    ______________________________________    Molded product (1)                  yellow streak,   good    (Example 7)   2 mm wide    Molded product (2)                  no change        excellent    (Example 8)    Molded product (3)                  no change        excellent    (Example 9)    Molded product (4)                  no change        excellent    (Example 10)    Molded product (5)                  no change        excellent    (Example 11)    Molded product (6)                  no change        excellent    (Example 12)    Molded product (7)                  no change        excellent    (Example 13)    Molded product (8)                  no change        excellent    (Example 14)    Molded product (9)                  yellow trace with white                                   poor    (Comp. Example 4)                  periphery, 4 mm wide    Molded product (11)                  brown scorch,    (Comp. Example 6)                  5 mm wide        poor    Molded product (12)                  brown scorch,    poor    (Comp. Example 7)                  5 mm wide    ______________________________________

It is noted from Table 4 that the molded products obtained in Examplesare superior in resistance to a live cigarette to those obtained inComparative Examples.

What is claimed is:
 1. A reactive particulate resin, each particle ofwhich comprises a core of a three-dimensionally crosslinked resin havinga degree of crosslinking from 0.05 to 2.0 mmol/g, and a shell formedthereon having a radical-polymerizable ethylenic unsaturated bond, saidshell being formed by polymerization of one or more polyfunctionalmonomers (A) and one or more non-aromatic radical-polymerizable monomers(B), said polyfunctional monomers (A) accounting for 1-50% of the totalmonomers from which the shell is formed and having in the molecule (a)at least one species of 1-monosubstituted and 1,1-disubstitutedradical-polymerizable ethylenic unsaturated bonds and (b) at least oneof at least one species of 1,2-disubstituted, 1,1,2-trisubstituted and1,1,2,2-tetrasubstituted radical-polymerizable ethylenic unsaturatedbonds.
 2. A reactive particulate resin as claimed in claim 1, whereinthe core particle is formed by emulsion polymerization of avinyl-polymerizable monomer and a crosslinkable monomer having at leasttwo copolymerizable ethylenic unsaturated bonds, with the amount of themonomers being such that the core particle has a degree of crosslinkingfrom 0.05 to 2.0 mmol/g.
 3. A reactive particulate resin as claimed inclaim 1, wherein the core particle is formed by emulsion polymerizationfrom a mixture of a polyfunctional monomer (A), a radical-polymerizablemonomer (B), and a polyfunctional monomer (C) having in the molecule atleast two of at least one species of 1-monosubstituted and1,1-disubstituted radical-polymerizable ethylenic unsaturated bonds. 4.A reactive particulate resin as claimed in claim 1, wherein thepolyfunctional monomer (A) has an acrylate type or methacrylate typeethylenic unsaturated bond (a) and a maleate type or fumarate typeethylenic unsaturated bond (b).
 5. A reactive particulate resin asclaimed in claim 1, wherein the polyfunctional monomer (A) is a monomerwhich is obtained by reacting a compound (a) having an ethylenicunsaturated bond selected from the group consisting of (meth)acrylatehaving hydroxy group, (meth)acrylate acid, (meth)acrylic halide,(meth)acrylate having epoxy group, and (meth)acrylate having isocyanategroup, with a compound (b) having an ethylenic unsaturated bond selectedfrom the group consisting of maleic anhydride, maleic acid, fumaricacid, glutaconic acid, mono alkyl maleate, mono alkyl fumarate, β-chloroacrylic acid, (iso)crotonic acid, α-substituted (iso)crotonic acid,β-substituted crotonic acid, crotyl alcohol, crotonaldehyde, angelicacid, tiglic acid, citraconic acid, citraconic anhydride, mesaconicacid, halo maleic acid, halo fumaric acid, aconitic acid, teraconic acidand mono alkyl ester of these acids.
 6. A reactive particulate resin asclaimed in claim 1, the polyfunctional monomer (A) is a monomer which isselected from the group consisting of a reaction product of maleicanhydride and 2-hydroxyethyl (meth)acrylate, a reaction product ofmonobutyl maleate and glycidyl (meth)acrylate, a reaction product of(meth)acrylic chloride and crotyl alcohol, and a reaction product of2-hydroxy-ethyl (meth)acrylate and citraconic anhydride.
 7. A reactiveparticulate resin as claimed in claim 1, whose particles have an averageparticle diameter in the range from 0.01 to 5 μm.
 8. A reactiveparticulate resin as claimed in claim 1, wherein the ratio (by weight)of the core particle to the shell is in the range from 10/90 to 99/1. 9.A reactive particulate resin as claimed in claim 1, wherein thecrosslinked resin of the core is formed from one or more ethylenicallyunsaturated monomers and the shell is formed by polymerizing one or moreunsaturated polyfunctional monomers and one or more unsaturatednon-aromatic radical-polymerizable monomers.
 10. A reactive particulateresin as claimed in claim 1, wherein the non-aromaticradical-polymerizable monomer (B) is methyl acrylate, methylmethacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate,n-butyl methacrylate, isobutyl acrylate, 2-ethylhexyl acrylate, laurylmethacrylate, or phenyl acrylate.
 11. A method for producing a reactiveparticulate resin which comprises a first step of synthesizing particlecores of three-dimensionally crosslinked resin having a degree ofcrosslinking in the range from 0.05 to 2.0 mmol/g, and a second step offorming on the surface of said particle core a shell having aradical-polymerizable ethylenic unsaturated bond, by polymerization ofone or more polyfunctional monomers (A) and one of more non-aromaticradical-polymerizable monomers (B), said polyfunctional monomer (A)accounting for 1-50% of the total monomers from which the shell isformed and having in the molecule (a) at least one species of1-monosubstituted and 1,1-disubstituted radical-polymerizable ethylenicunsaturated bonds and (b) at least one of at least one species of1,2-disubstituted, 1,1,2-trisubstituted, and 1,1,2,2-tetrasubstitutedradical-polymerizable ethylenic unsaturated bonds.
 12. A methodaccording to claim 11, wherein the crosslinked resin of the core isformed from one or more ethylenically unsaturated monomers.